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inter.noise 2000The 29th International Congress and Exhibition on Noise Control Engineering27-30 August 2000, Nice, FRANCE

I-INCE Classification: 6.1

TOWARD A CHARACTERISATION OF THE SONICENVIRONMENT: THE METHOD OF QUALIFIED

LISTENING IN MOTION

N. Tixier

Laboratoire Cresson - UMR CNRS 1563, Ecole d’Architecture de Grenoble - 60 Avenue de Constantine- BP 2636, 38036, Grenoble, France

Tel.: 33 (0)4 76 23 41 90 / Fax: 33 (0)4 76 69 83 73 / Email: nicolas.tixier@grenoble.archi.fr

Keywords:SOUND ENVIRONMENT, IN SITU METHODOLOGY, SOUNDS EFFECTS

ABSTRACTUrban sonic environment requires an interdisciplinary approach which looks both at its physical andspatial dimensions as well as its perceptual and social dimensions. The method of ” qualified listening inmotion ” aims, after an architectural and urban statement, to produce in situ a set of verbal accounts ofperception. Starting from these first qualifications, a metrological campaign, ethnographic observationsand sound recordings are carried out. The comparison of this data enable to highlight and identifyspecific sound indicators of the environment such as recurrent sonic effects [Augoyard, Cresson, 1995].By including perception and action of city dwellers in context, this method makes it possible to revealthe strong temporal (events, dynamics) and symbolic (meaning, emotions, discursive) characteristics ofsound in the urban environment as much in its qualitative and quantitative dimensions. This methodwas applied in an exploratory way to two French urban sites: the Z.A.C. Vigny-Musset in Grenoble (38)and the district of the Port au Ble in Reze (44). This work was performed in collaboration with NicolasBoyer under the direction of Jean-Francois Augoyard.

1 - INTRODUCTIONWe have been developing an approach based on a more qualitative study of the sound environmentwhich will complement in a preparatory fashion the usual metrological surveying techniques used inurban acoustics. It is directly based on the notion of atmosphere (called ”ambiance” in French [1]) andthe descriptive and interpretative tools, namely, the sound effects [2]. This method was developed incollaboration with Nicolas Boyer. It has been used in an exploratory fashion in several research projects[3], [4] with the interdisciplinary collaboration of other laboratories, such as the CERMA and the LCPCin Nantes, or the LAUM in Mans. Two sites were used for this study: the Z.A.C. Vigny-Musset inGrenoble (Isere), and the Port au Ble district in Reze (Loire-Atlantique).

2 - METHODOLOGYApproaching a ”sound atmosphere” (”ambiances sonores”) involves an interdisciplinary process takinginto account both the physical and the constructed dimensions of the space, as well as the social andperspective dimensions given to it by the users. We will thus make the triple postulate of an approachwhich will be: urban, in situ and dynamic. Our commented-listening (ecoute qualifiee) method stemsdirectly from the method of the commented circuits [5]. The next step after an architectural and urbansurvey is to obtain the reports of what is perceived whilst moving thanks to a recording device and anacoustic amplification.The listening subject is fitted out with two systems of synchronised recording equipment:

1. The amplified listening apparatus: a directional microphone + a pole that the listener directshimself + D.A.T. recording of the sound environment + headphones (the band is adjusted todB(A) level to enable a later metrological analysis).

2. Comments: a small lapel mounted microphone + Dictaphone recording of the descriptions.

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Figure 1: Walking, listening and describing.

This technical apparatus, thanks to the emphasis its lays on the surrounding sounds, helps the participantspeak of what is usually taken for granted and is thus difficult to express, namely our usual soundenvironment. A researcher accompanies the participant to guide him and to encourage him to speakwhen necessary. His presence is also necessary to put the comments into context and note their relativeimportance. The participants are mainly selected on the basis of their connections − or lack of them −to the studied space: lodgings, work, shops, school, walks, gardens... They went round the circuits atdifferent times of the day and on different days, and even in different weather conditions. From fifteencandidates onwards, it was soon clear from the amount of repetition within the comments, that is waspossible to circumscribe the different phenomenon

Figure 2: General methodology.

3 - ANALYSISThe qualitative analysis of the participant’s comments in response to the built environment is donefollowing a technique called ”table and scissors” (la table et les ciseaux) (a phrase coined by Y. Chalas[6]). This technique is often used for the construction of typologies, and in figurative analysis (analysefigurative). The sequencing into meaningful entities is done following five modes of apprehending sounds.The first three correspond to three of the four ways of listening listed by Pierre Schaeffer [7] namely:perception (unprocessed sounds, ”ouır”), hearing (qualitative perception or perceptions qualifiees,”entendre”) and listening (indications, ”ecouter”). The analysis of the comments implies the adjunctionof two more criteria: the sounds directly linked to the participants and the statements which qualifythe sound space in a more general way. This second stage enables us to list the qualities and the soundphenomenon according to the different spaces and transitions studied. This enables us to select what ismajor and sufficiently recurrent within the sound environment to record and measure the characteristicsof these phenomenon in a third stage. Finally, an analysis combining these three types of data (comments,recordings and measurements) enables us to specify what the more noteworthy sound atmospheres ofthe site.

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4 - EXAMPLETo illustrate this method, here is a simplified example of two ”mask” effects on a short sequence takenfrom the Nantes study (Reze). The participant walks along a two lane road lined with low buildings, skirtsa rather busy roundabout, walks away from it, then along a pavement, to finally enter an open-spacewhere there is a tram stop.

Figure 3: [Bus + Tram: levels dB(A)] two ”mask” effects/ two different perceptions.

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Recording(D.A.T.)

Interesting expressions(extracts) (Dictaphone)

Descrip-tion of

thesoundeffect

Tempo-ralitySe-

quence

Indicativemea-sure-ments

Synthesis,Comments

. . .Flow ofcars • ”... In fact, the cars

make such a noisethat any other soundis drowned out. I cansee the tram, but Ican’t even hear it.”

• ”a moped, but I didnot really hear it.One can’t hear anybirds at all.”

• ”And so this is...well there I could notsay a thing, it wasimpossible to hearanything.”

”Mask”Conti-nuum

Conti-nuous

Leq(10 s)

= 63dB(A)(duringtraffic)

The participantseven stop talking(the cars drowntheir voices) andwait until thenoise has dieddown or untilthey have walkedfurther.In general peoplewalk faster wentskirting theroundabout.

. . .The tramgoes by(It’s arrival,bell rings, itbrakes, thedoors open,passengersget on andoff, the doorsclose, itdrives away)

• ”I can hear... yes,...faintly hear thetram.”

• ”Now I can hear thetram going by.”

• ”The tram is pullingaway, my ears areringing slightly.”

• ”The tram bells”

• ”Whirrrrrrr, it ispulling away, I canhear it clearly”

• ”And here comes atram... now... it isslowingdown...whizzzz....now, it is whistlingagain. It’s stopping.”

Emer-genceCrescen-doSignal”Mask”

Narra-tiveSeriesofevents

Leq(10 s)

=75 dB(A)(whenthe tramcomes)Lmax =84 dB(A)

People note thetram’s arrival farmore than itsdeparture.Narrativesequence.

. . .

Table 1: Cross-referencing of different types of material (extract).

There are two occurrences of the ”mask” effect within this short walk linked to the passage of cars.The first one is generated by the traffic at the roundabout. It is characterised by several factors. Firstof all, people express it in a direct manner: ”the cars make such a noise any other sound is drownedout”. Secondly, they also express it in a more indirect way, through its impregnation on the generalcontext: ”I can see the tram but I can’t even hear it”. Thirdly, it is noticeable when listening to thecomments themselves that the subjects stop talking and only resume their commentary once they have

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left the roundabout. Fourthly it is recorded and fifthly it is characterised by a measurement. Thiseffect is generally perceived as being a nuisance, people walk faster when they go past and this negativeconnotation is found in the different comments, going as far even as the obliteration of all identity: ”itis impossible to hear anything”, when in fact one can clearly hear it.On the contrary, the ”mask” effect created by the tram’s arrival is never perceived as a nuisance whereasthe noise level is clearly more important. The sound characteristics of the tramway and its use havethe dual characteristic of forming a series of events limited in time (whereas car traffic partakes of acontinuum) and part of a narrative (the series of events forming a meaningful sequence).

5 - CONCLUSIONThe localisation and the characterisation of the meaningful sound phenomenon render a metrologicaleconomy possible, whilst answering the classical questions on the acoustic evaluation of a large urbanzone: what should one measure, where, when, and using what types of measures and analysis? Thiscomplementary approach to the more classical techniques enable us to widen the field of the observable inacoustic metrology thanks to an interdisciplinary combination of the sound phenomenon (characterisationof the built surroundings, of the activities, urban perceptions, measures and temporality ...) Furthermore,the measures and recordings only grasp certain dimensions of the perceived sound environment. Takingthe circuit as a basis, the urban speech and way of listening introduce fundamental parameters to thequalification of atmosphere, namely the time dynamics and the interaction of the city dwellersto their surroundings.Translator’s note: ”qualified listening” includes the idea of quality and of qualifying, describing.

ACKNOWLEDGEMENTSTranslation by Anne-Marie TATHAM.

REFERENCES

1. J.-F. Augoyard, L’environnement sensible et les ambiances architecturales, L’espace geographique,Vol. 4, pp. 302-318, 1995

2. J.-F. Augoyard and H. Torgue, A l’ecoute de l’environnement sonore. Repertoire des effetssonores, Parentheses, 1995

3. N. Boyer and N. Tixier, Qualification des sources sonores urbaines. Enquetes de terrain, Rap-port PIR-VILLES sous la direction de J.P. Peneau: vers un logiciel predictif des ambiances sonoresurbaines, 2000

4. N. Boyer and N. Tixier, Enquete par immersion interactive sur les procedures de maetrise desambiances sonore dans le projet architectural, Cresson - Ministere de la Culture et de la Com-munication, Sous la direction de J.-F. Augoyard Version Papier, version CDrom, version internet:http://www.cresson.archi.fr/E2I/Site/pages/home.htm, 2000

5. J.-P. Thibaud, La methode des parcours commentes in L’espace urbain en methodes, Parentheses,2000

6. Y. Chalas, Analyse figurative des pratiques d’habiter in L’espace urbain en methodes, Parentheses,2000

7. P. Schaeffer, Traite des objets musicaux, Seuil, 1966